Content resolution adjustment for passive display devices

ABSTRACT

Passive display devices such as a passive magnifying device (e.g., a screen magnifier) or a projector (e.g., a built-in mobile phone projector) are useful in enlarging photos, documents, videos, etc. for view for small-sized small-screen device screens. However, optimal content resolution for the small-screen device screens may not be optimal for the passive display devices. Particularly, when a small-screen device receives content from a remote computing device, the initial content resolution may not be optimal even for the small-screen device screen because of low transmission speed and/or low bandwidth of a connection with an original data source. Content resolution adjustment may be performed by determining distance between the passive display device and the small-screen device, calculating magnification ratio for the passive display device, and adjusting the content resolution based on the calculated magnification ratio.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to pending U.S. application Ser. No.16/815,483, filed Mar. 11, 2020, and having the title “ContentResolution Adjustment for Passive Display Devices,” which in turn claimspriority to International Application No. PCT/CN2020/071895, filed Jan.14, 2020, and entitled “Content Resolution Adjustment for PassiveDisplay Devices,” each of which is hereby incorporated by reference inits entirety.

FIELD

Aspects described herein generally relate to computer hardware andsoftware configured to adjust content resolution for passive displaydevices. More specifically, one or more aspects describe herein provideoptimal resolution output via passive display devices for contentreceived by a small-screen device from a remote-access system, avirtualized system, a cloud-based system, and/or an enterprise mobilitymanagement system.

BACKGROUND

Small-screen devices (e.g., mobile phone, smartphone, personal digitalassistant (PDA), notebook, iPod Touch, client device, terminal, etc.)are used more and more widely by enterprises and individuals. When usedfor business, small-screen devices sometimes are used to view and sharecompany documents. When used in daily activities, small-screen devicessometimes are used in viewing and sharing photos, browsing the internet,watching entertainment videos, etc. In these scenarios, the viewingexperience is limited by the small sizes of the small-screen devices'screens. Passive display devices such as a passive magnifying device(e.g., a screen magnifier) or a projector (e.g., a built-in mobile phoneprojector, a wireless projector, etc.) may be utilized to enlarge thecontent size for a better viewing experience. However, the contentresolution that is optimal for the small-screen device screen viewingmay not be optimal for the passive display device viewing.

SUMMARY

The following presents a simplified summary of various aspects describedherein. This summary is not an extensive overview, and is not intendedto identify required or critical elements or to delineate the scope ofthe claims. The following summary merely presents some concepts in asimplified form as an introductory prelude to the more detaileddescription provided below.

To overcome limitations in the prior art described above, and toovercome other limitations that will be apparent upon reading andunderstanding the present specification, aspects described herein aredirected towards content resolution adjustment for passive displaydevices.

When content is output on a screen of a small-screen device, the contentmay be in a first resolution. To adjust the content resolution for viewon a passive magnifying device (e.g., a screen magnifier), thesmall-screen device may determine a maximum screen resolution, a maximumPixels Per Inch (PPI), and a screen size of the screen of thesmall-screen device. The small-screen device may further determine afocal length, a preferred view screen resolution, and a screen size of ascreen of the passive magnifying device. The focal length may be used tocalculate a magnification ratio of the passive magnifying device. Inaddition to the focal length, to calculate the magnification ratio, adistance between the small-screen device screen and the passivemagnifying device screen needs to be determined by the small-screendevice. Based on the calculated magnification ratio, the small-screendevice may adjust the content on the screen of the small-screen deviceto a second resolution to provide the preferred view screen resolutionof the content on the screen of the passive magnifying device.

Similarly, to adjust the content resolution for optimal view on a screen(e.g., a projector screen, a wall, an object, etc.) for a projector(e.g., a built-in mobile phone projector, a wireless projector, etc.), asize of a projected content needs to be calculated. The projector mayproject the content onto the screen. The small-screen device maydetermine specifications (e.g., an aperture width, a focal length, etc.)of the projector. The small-screen device may determine a distancebetween the projector and the screen. The size of the projected contentmay be calculated based on the determined distance and thespecifications of the projector. A preferred view screen resolution maybe determined based on the calculated size of the projected content. Thesmall-screen device may then adjust the content on the screen of thesmall-screen device to a second resolution matching the preferred viewscreen resolution of the content on the screen.

These and additional aspects will be appreciated with the benefit of thedisclosures discussed in further detail below.

BRIEF DESCRIPTION OF THE DRAWINGS

A more complete understanding of aspects described herein and theadvantages thereof may be acquired by referring to the followingdescription in consideration of the accompanying drawings, in which likereference numbers indicate like features, and wherein:

FIG. 1 depicts an illustrative computer system architecture that may beused in accordance with one or more illustrative aspects describedherein.

FIG. 2 depicts an illustrative remote-access system architecture thatmay be used in accordance with one or more illustrative aspectsdescribed herein.

FIG. 3 depicts an illustrative virtualized system architecture that maybe used in accordance with one or more illustrative aspects describedherein.

FIG. 4 depicts an illustrative cloud-based system architecture that maybe used in accordance with one or more illustrative aspects describedherein.

FIG. 5 depicts an illustrative enterprise mobility management system.

FIG. 6 depicts another illustrative enterprise mobility managementsystem.

FIG. 7 depicts an illustrative system architecture comprising a passivemagnifying device.

FIG. 8 depicts an illustrative optical magnification mechanism for apassive magnifying device and an illustrative projection mechanism for aprojector.

FIG. 9 depicts illustrative screenshots used to determine distance witha captured image.

FIG. 10 depicts illustrative screenshots used to determine systemparameters.

FIG. 11 depicts an illustrative system architecture comprising aprojector.

FIG. 12 is a flow chart showing a method of content resolutionadjustment comprising a passive magnifying device.

FIG. 13 is a flow chart showing a method of determining distance with acaptured image.

FIG. 14 is a flow chart showing a method of triggering contentresolution adjustment.

FIG. 15 is a flow chart showing a method of adjusting content resolutionto maximum screen resolution.

FIG. 16 is a flow chart showing a method of adjusting content resolutionbased on maximum PPI.

FIG. 17 is a flow chart showing a method of content resolutionadjustment comprising a projector.

DETAILED DESCRIPTION

As a general introduction to the subject matter described in more detailbelow, aspects described herein are directed towards content resolutionadjustment for passive display devices. The same content resolution thatis optimal for a small-screen device viewing may not be optimal for thepassive display device viewing. Particularly, if the content is receivedfrom a remote-access system, a virtualized system, a cloud-based system,an enterprise mobility management system, etc., the content received maybe in a dissatisfying resolution even for the small-screen devicebecause of low transmission speed, low bandwidth, etc., of a connectionwith an original data source. In this specification, the first part isdedicated to computing architecture depicting illustrative generalcomputer system, remote-access system, virtualized system, cloud-basedsystem, and enterprise mobility management architecture depictingillustrative enterprise mobility management systems, that may sendcontent to the small-screen device for view. The second part isdedicated to methods and systems for adjusting content resolution by thesmall-screen device for view via the passive display devices such as apassive magnifying device (e.g., a screen magnifier) or a projector(e.g., a built-in mobile phone projector, a wireless projector, etc.).

Computing Architecture

Computer software, hardware, and networks may be utilized in a varietyof different system environments, including standalone, networked,remote-access (also known as remote desktop), virtualized, and/orcloud-based environments, among others. FIG. 1 illustrates one exampleof a system architecture and data processing device that may be used toimplement one or more illustrative aspects described herein in astandalone and/or networked environment. Various network nodes 103, 105,107, and 109 may be interconnected via a wide area network (WAN) 101,such as the Internet. Other networks may also or alternatively be used,including private intranets, corporate networks, local area networks(LAN), metropolitan area networks (MAN), wireless networks, personalnetworks (PAN), and the like. Network 101 is for illustration purposesand may be replaced with fewer or additional computer networks. A localarea network 133 may have one or more of any known LAN topology and mayuse one or more of a variety of different protocols, such as Ethernet.Devices 103, 105, 107, and 109 and other devices (not shown) may beconnected to one or more of the networks via twisted pair wires, coaxialcable, fiber optics, radio waves, or other communication media.

The term “network” as used herein and depicted in the drawings refersnot only to systems in which remote storage devices are coupled togethervia one or more communication paths, but also to stand-alone devicesthat may be coupled, from time to time, to such systems that havestorage capability. Consequently, the term “network” includes not only a“physical network” but also a “content network,” which is comprised ofthe data—attributable to a single entity—which resides across allphysical networks.

The components may include data server 103, web server 105, and clientcomputers 107, 109. Data server 103 provides overall access, control andadministration of databases and control software for performing one ormore illustrative aspects describe herein. Data server 103 may beconnected to web server 105 through which users interact with and obtaindata as requested. Alternatively, data server 103 may act as a webserver itself and be directly connected to the Internet. Data server 103may be connected to web server 105 through the local area network 133,the wide area network 101 (e.g., the Internet), via direct or indirectconnection, or via some other network. Users may interact with the dataserver 103 using remote computers 107, 109, e.g., using a web browser toconnect to the data server 103 via one or more externally exposed websites hosted by web server 105. Client computers 107, 109 may be used inconcert with data server 103 to access data stored therein, or may beused for other purposes. For example, from client device 107 a user mayaccess web server 105 using an Internet browser, as is known in the art,or by executing a software application that communicates with web server105 and/or data server 103 over a computer network (such as theInternet).

Servers and applications may be combined on the same physical machines,and retain separate virtual or logical addresses, or may reside onseparate physical machines. FIG. 1 illustrates just one example of anetwork architecture that may be used, and those of skill in the artwill appreciate that the specific network architecture and dataprocessing devices used may vary, and are secondary to the functionalitythat they provide, as further described herein. For example, servicesprovided by web server 105 and data server 103 may be combined on asingle server.

Each component 103, 105, 107, 109 may be any type of known computer,server, or data processing device. Data server 103, e.g., may include aprocessor 111 controlling overall operation of the data server 103. Dataserver 103 may further include random access memory (RAM) 113, read onlymemory (ROM) 115, network interface 117, input/output interfaces 119(e.g., keyboard, mouse, display, printer, etc.), and memory 121.Input/output (I/O) 119 may include a variety of interface units anddrives for reading, writing, displaying, and/or printing data or files.Memory 121 may further store operating system software 123 forcontrolling overall operation of the data processing device 103, controllogic 125 for instructing data server 103 to perform aspects describedherein, and other application software 127 providing secondary, support,and/or other functionality which may or might not be used in conjunctionwith aspects described herein. The control logic 125 may also bereferred to herein as the data server software 125. Functionality of thedata server software 125 may refer to operations or decisions madeautomatically based on rules coded into the control logic 125, mademanually by a user providing input into the system, and/or a combinationof automatic processing based on user input (e.g., queries, dataupdates, etc.).

Memory 121 may also store data used in performance of one or moreaspects described herein, including a first database 129 and a seconddatabase 131. In some embodiments, the first database 129 may includethe second database 131 (e.g., as a separate table, report, etc.). Thatis, the information can be stored in a single database, or separatedinto different logical, virtual, or physical databases, depending onsystem design. Devices 105, 107, and 109 may have similar or differentarchitecture as described with respect to device 103. Those of skill inthe art will appreciate that the functionality of data processing device103 (or device 105, 107, or 109) as described herein may be spreadacross multiple data processing devices, for example, to distributeprocessing load across multiple computers, to segregate transactionsbased on geographic location, user access level, quality of service(QoS), etc.

One or more aspects may be embodied in computer-usable or readable dataand/or computer-executable instructions, such as in one or more programmodules, executed by one or more computers or other devices as describedherein. Generally, program modules include routines, programs, objects,components, data structures, etc. that perform particular tasks orimplement particular abstract data types when executed by a processor ina computer or other device. The modules may be written in a source codeprogramming language that is subsequently compiled for execution, or maybe written in a scripting language such as (but not limited to)HyperText Markup Language (HTML) or Extensible Markup Language (XML).The computer executable instructions may be stored on a computerreadable medium such as a nonvolatile storage device. Any suitablecomputer readable storage media may be utilized, including hard disks,CD-ROMs, optical storage devices, magnetic storage devices, solid statestorage devices, and/or any combination thereof. In addition, varioustransmission (non-storage) media representing data or events asdescribed herein may be transferred between a source and a destinationin the form of electromagnetic waves traveling through signal-conductingmedia such as metal wires, optical fibers, and/or wireless transmissionmedia (e.g., air and/or space). Various aspects described herein may beembodied as a method, a data processing system, or a computer programproduct. Therefore, various functionalities may be embodied in whole orin part in software, firmware, and/or hardware or hardware equivalentssuch as integrated circuits, field programmable gate arrays (FPGA), andthe like. Particular data structures may be used to more effectivelyimplement one or more aspects described herein, and such data structuresare contemplated within the scope of computer executable instructionsand computer-usable data described herein.

With further reference to FIG. 2, one or more aspects described hereinmay be implemented in a remote-access environment. FIG. 2 depicts anexample system architecture including a computing device 201 in anillustrative computing environment 200 that may be used according to oneor more illustrative aspects described herein. Computing device 201 maybe used as a server 206 a in a single-server or multi-server desktopvirtualization system (e.g., a remote access or cloud system) and can beconfigured to provide virtual machines for client access devices. Thecomputing device 201 may have a processor 203 for controlling overalloperation of the device 201 and its associated components, including RAM205, ROM 207, Input/Output (I/O) module 209, and memory 215.

I/O module 209 may include a mouse, keypad, touch screen, scanner,optical reader, and/or stylus (or other input device(s)) through which auser of computing device 201 may provide input, and may also include oneor more of a speaker for providing audio output and one or more of avideo display device for providing textual, audiovisual, and/orgraphical output. Software may be stored within memory 215 and/or otherstorage to provide instructions to processor 203 for configuringcomputing device 201 into a special purpose computing device in order toperform various functions as described herein. For example, memory 215may store software used by the computing device 201, such as anoperating system 217, application programs 219, and an associateddatabase 221.

Computing device 201 may operate in a networked environment supportingconnections to one or more remote computers, such as terminals 240 (alsoreferred to as client devices and/or client machines). The terminals 240may be personal computers, mobile devices, laptop computers, tablets, orservers that include many or all of the elements described above withrespect to the computing device 103 or 201. The network connectionsdepicted in FIG. 2 include a local area network (LAN) 225 and a widearea network (WAN) 229, but may also include other networks. When usedin a LAN networking environment, computing device 201 may be connectedto the LAN 225 through a network interface or adapter 223. When used ina WAN networking environment, computing device 201 may include a modemor other wide area network interface 227 for establishing communicationsover the WAN 229, such as computer network 230 (e.g., the Internet). Itwill be appreciated that the network connections shown are illustrativeand other means of establishing a communications link between thecomputers may be used. Computing device 201 and/or terminals 240 mayalso be mobile terminals (e.g., mobile phones, smartphones, personaldigital assistants (PDAs), notebooks, etc.) including various othercomponents, such as a battery, speaker, and antennas (not shown).

Aspects described herein may also be operational with numerous othergeneral purpose or special purpose computing system environments orconfigurations. Examples of other computing systems, environments,and/or configurations that may be suitable for use with aspectsdescribed herein include, but are not limited to, personal computers,server computers, hand-held or laptop devices, multiprocessor systems,microprocessor-based systems, set top boxes, programmable consumerelectronics, network personal computers (PCs), minicomputers, mainframecomputers, distributed computing environments that include any of theabove systems or devices, and the like.

As shown in FIG. 2, one or more client devices 240 may be incommunication with one or more servers 206 a-206 n (generally referredto herein as “server(s) 206”). In one embodiment, the computingenvironment 200 may include a network appliance installed between theserver(s) 206 and client machine(s) 240. The network appliance maymanage client/server connections, and in some cases can load balanceclient connections amongst a plurality of backend servers 206.

The client machine(s) 240 may in some embodiments be referred to as asingle client machine 240 or a single group of client machines 240,while server(s) 206 may be referred to as a single server 206 or asingle group of servers 206. In one embodiment a single client machine240 communicates with more than one server 206, while in anotherembodiment a single server 206 communicates with more than one clientmachine 240. In yet another embodiment, a single client machine 240communicates with a single server 206.

A client machine 240 can, in some embodiments, be referenced by any oneof the following non-exhaustive terms: client machine(s); client(s);client computer(s); client device(s); client computing device(s); localmachine; remote machine; client node(s); endpoint(s); or endpointnode(s). The server 206, in some embodiments, may be referenced by anyone of the following non-exhaustive terms: server(s), local machine;remote machine; server farm(s), or host computing device(s).

In one embodiment, the client machine 240 may be a virtual machine. Thevirtual machine may be any virtual machine, while in some embodimentsthe virtual machine may be any virtual machine managed by a Type 1 orType 2 hypervisor, for example, a hypervisor developed by CitrixSystems, IBM, VMware, or any other hypervisor. In some aspects, thevirtual machine may be managed by a hypervisor, while in other aspectsthe virtual machine may be managed by a hypervisor executing on a server206 or a hypervisor executing on a client 240.

Some embodiments include a client device 240 that displays applicationoutput generated by an application remotely executing on a server 206 orother remotely located machine. In these embodiments, the client device240 may execute a virtual machine receiver program or application todisplay the output in an application window, a browser, or other outputwindow. In one example, the application is a desktop, while in otherexamples the application is an application that generates or presents adesktop. A desktop may include a graphical shell providing a userinterface for an instance of an operating system in which local and/orremote applications can be integrated. Applications, as used herein, areprograms that execute after an instance of an operating system (and,optionally, also the desktop) has been loaded.

The server 206, in some embodiments, uses a remote presentation protocolor other program to send data to a thin-client or remote-displayapplication executing on the client to present display output generatedby an application executing on the server 206. The thin-client orremote-display protocol can be any one of the following non-exhaustivelist of protocols: the Independent Computing Architecture (ICA) protocoldeveloped by Citrix Systems, Inc. of Ft. Lauderdale, Fla.; or the RemoteDesktop Protocol (RDP) manufactured by the Microsoft Corporation ofRedmond, Wash.

A remote computing environment may include more than one server 206a-206 n such that the servers 206 a-206 n are logically grouped togetherinto a server farm 206, for example, in a cloud computing environment.The server farm 206 may include servers 206 that are geographicallydispersed while logically grouped together, or servers 206 that arelocated proximate to each other while logically grouped together.Geographically dispersed servers 206 a-206 n within a server farm 206can, in some embodiments, communicate using a WAN (wide), MAN(metropolitan), or LAN (local), where different geographic regions canbe characterized as: different continents; different regions of acontinent; different countries; different states; different cities;different campuses; different rooms; or any combination of the precedinggeographical locations. In some embodiments the server farm 206 may beadministered as a single entity, while in other embodiments the serverfarm 206 can include multiple server farms.

In some embodiments, a server farm may include servers 206 that executea substantially similar type of operating system platform (e.g.,WINDOWS, UNIX, LINUX, iOS, ANDROID, etc.) In other embodiments, serverfarm 206 may include a first group of one or more servers that execute afirst type of operating system platform, and a second group of one ormore servers that execute a second type of operating system platform.

Server 206 may be configured as any type of server, as needed, e.g., afile server, an application server, a web server, a proxy server, anappliance, a network appliance, a gateway, an application gateway, agateway server, a virtualization server, a deployment server, a SecureSockets Layer (SSL) VPN server, a firewall, a web server, an applicationserver or as a master application server, a server executing an activedirectory, or a server executing an application acceleration programthat provides firewall functionality, application functionality, or loadbalancing functionality. Other server types may also be used.

Some embodiments include a first server 206 a that receives requestsfrom a client machine 240, forwards the request to a second server 206 b(not shown), and responds to the request generated by the client machine240 with a response from the second server 206 b (not shown.) Firstserver 206 a may acquire an enumeration of applications available to theclient machine 240 as well as address information associated with anapplication server 206 hosting an application identified within theenumeration of applications. First server 206 a can then present aresponse to the client's request using a web interface, and communicatedirectly with the client 240 to provide the client 240 with access to anidentified application. One or more clients 240 and/or one or moreservers 206 may transmit data over network 230, e.g., network 101.

FIG. 3 shows a high-level architecture of an illustrative desktopvirtualization system. As shown, the desktop virtualization system maybe single-server or multi-server system, or cloud system, including atleast one virtualization server 301 configured to provide virtualdesktops and/or virtual applications to one or more client accessdevices 240. As used herein, a desktop refers to a graphical environmentor space in which one or more applications may be hosted and/orexecuted. A desktop may include a graphical shell providing a userinterface for an instance of an operating system in which local and/orremote applications can be integrated. Applications may include programsthat execute after an instance of an operating system (and, optionally,also the desktop) has been loaded. Each instance of the operating systemmay be physical (e.g., one operating system per device) or virtual(e.g., many instances of an OS running on a single device). Eachapplication may be executed on a local device, or executed on a remotelylocated device (e.g., remoted).

A computer device 301 may be configured as a virtualization server in avirtualization environment, for example, a single-server, multi-server,or cloud computing environment. Virtualization server 301 illustrated inFIG. 3 can be deployed as and/or implemented by one or more embodimentsof the server 206 illustrated in FIG. 2 or by other known computingdevices. Included in virtualization server 301 is a hardware layer thatcan include one or more physical disks 304, one or more physical devices306, one or more physical processors 308, and one or more physicalmemories 316. In some embodiments, firmware 312 can be stored within amemory element in the physical memory 316 and can be executed by one ormore of the physical processors 308. Virtualization server 301 mayfurther include an operating system 314 that may be stored in a memoryelement in the physical memory 316 and executed by one or more of thephysical processors 308. Still further, a hypervisor 302 may be storedin a memory element in the physical memory 316 and can be executed byone or more of the physical processors 308.

Executing on one or more of the physical processors 308 may be one ormore virtual machines 332A-C (generally 332). Each virtual machine 332may have a virtual disk 326A-C and a virtual processor 328A-C. In someembodiments, a first virtual machine 332A may execute, using a virtualprocessor 328A, a control program 320 that includes a tools stack 324.Control program 320 may be referred to as a control virtual machine,Dom0, Domain 0, or other virtual machine used for system administrationand/or control. In some embodiments, one or more virtual machines 332B-Ccan execute, using a virtual processor 328B-C, a guest operating system330A-B.

Virtualization server 301 may include a hardware layer 310 with one ormore pieces of hardware that communicate with the virtualization server301. In some embodiments, the hardware layer 310 can include one or morephysical disks 304, one or more physical devices 306, one or morephysical processors 308, and one or more physical memory 316. Physicalcomponents 304, 306, 308, and 316 may include, for example, any of thecomponents described above. Physical devices 306 may include, forexample, a network interface card, a video card, a keyboard, a mouse, aninput device, a monitor, a display device, speakers, an optical drive, astorage device, a universal serial bus connection, a printer, a scanner,a network element (e.g., router, firewall, network address translator,load balancer, virtual private network (VPN) gateway, Dynamic HostConfiguration Protocol (DHCP) router, etc.), or any device connected toor communicating with virtualization server 301. Physical memory 316 inthe hardware layer 310 may include any type of memory. Physical memory316 may store data, and in some embodiments may store one or moreprograms, or set of executable instructions. FIG. 3 illustrates anembodiment where firmware 312 is stored within the physical memory 316of virtualization server 301. Programs or executable instructions storedin the physical memory 316 can be executed by the one or more processors308 of virtualization server 301.

Virtualization server 301 may also include a hypervisor 302. In someembodiments, hypervisor 302 may be a program executed by processors 308on virtualization server 301 to create and manage any number of virtualmachines 332. Hypervisor 302 may be referred to as a virtual machinemonitor, or platform virtualization software. In some embodiments,hypervisor 302 can be any combination of executable instructions andhardware that monitors virtual machines executing on a computingmachine. Hypervisor 302 may be Type 2 hypervisor, where the hypervisorexecutes within an operating system 314 executing on the virtualizationserver 301. Virtual machines may then execute at a level above thehypervisor 302. In some embodiments, the Type 2 hypervisor may executewithin the context of a user's operating system such that the Type 2hypervisor interacts with the user's operating system. In otherembodiments, one or more virtualization servers 301 in a virtualizationenvironment may instead include a Type 1 hypervisor (not shown). A Type1 hypervisor may execute on the virtualization server 301 by directlyaccessing the hardware and resources within the hardware layer 310. Thatis, while a Type 2 hypervisor 302 accesses system resources through ahost operating system 314, as shown, a Type 1 hypervisor may directlyaccess all system resources without the host operating system 314. AType 1 hypervisor may execute directly on one or more physicalprocessors 308 of virtualization server 301, and may include programdata stored in the physical memory 316.

Hypervisor 302, in some embodiments, can provide virtual resources tooperating systems 330 or control programs 320 executing on virtualmachines 332 in any manner that simulates the operating systems 330 orcontrol programs 320 having direct access to system resources. Systemresources can include, but are not limited to, physical devices 306,physical disks 304, physical processors 308, physical memory 316, andany other component included in hardware layer 310 of the virtualizationserver 301. Hypervisor 302 may be used to emulate virtual hardware,partition physical hardware, virtualize physical hardware, and/orexecute virtual machines that provide access to computing environments.In still other embodiments, hypervisor 302 may control processorscheduling and memory partitioning for a virtual machine 332 executingon virtualization server 301. Hypervisor 302 may include thosemanufactured by VMWare, Inc., of Palo Alto, Calif.; HyperV,VirtualServer or virtual PC hypervisors provided by Microsoft, orothers. In some embodiments, virtualization server 301 may execute ahypervisor 302 that creates a virtual machine platform on which guestoperating systems may execute. In these embodiments, the virtualizationserver 301 may be referred to as a host server. An example of such avirtualization server is the Citrix Hypervisor provided by CitrixSystems, Inc., of Fort Lauderdale, Fla.

Hypervisor 302 may create one or more virtual machines 332B-C (generally332) in which guest operating systems 330 execute. In some embodiments,hypervisor 302 may load a virtual machine image to create a virtualmachine 332. In other embodiments, the hypervisor 302 may execute aguest operating system 330 within virtual machine 332. In still otherembodiments, virtual machine 332 may execute guest operating system 330.

In addition to creating virtual machines 332, hypervisor 302 may controlthe execution of at least one virtual machine 332. In other embodiments,hypervisor 302 may present at least one virtual machine 332 with anabstraction of at least one hardware resource provided by thevirtualization server 301 (e.g., any hardware resource available withinthe hardware layer 310). In other embodiments, hypervisor 302 maycontrol the manner in which virtual machines 332 access physicalprocessors 308 available in virtualization server 301. Controllingaccess to physical processors 308 may include determining whether avirtual machine 332 should have access to a processor 308, and howphysical processor capabilities are presented to the virtual machine332.

As shown in FIG. 3, virtualization server 301 may host or execute one ormore virtual machines 332. A virtual machine 332 is a set of executableinstructions that, when executed by a processor 308, may imitate theoperation of a physical computer such that the virtual machine 332 canexecute programs and processes much like a physical computing device.While FIG. 3 illustrates an embodiment where a virtualization server 301hosts three virtual machines 332, in other embodiments virtualizationserver 301 can host any number of virtual machines 332. Hypervisor 302,in some embodiments, may provide each virtual machine 332 with a uniquevirtual view of the physical hardware, memory, processor, and othersystem resources available to that virtual machine 332. In someembodiments, the unique virtual view can be based on one or more ofvirtual machine permissions, application of a policy engine to one ormore virtual machine identifiers, a user accessing a virtual machine,the applications executing on a virtual machine, networks accessed by avirtual machine, or any other desired criteria. For instance, hypervisor302 may create one or more unsecure virtual machines 332 and one or moresecure virtual machines 332. Unsecure virtual machines 332 may beprevented from accessing resources, hardware, memory locations, andprograms that secure virtual machines 332 may be permitted to access. Inother embodiments, hypervisor 302 may provide each virtual machine 332with a substantially similar virtual view of the physical hardware,memory, processor, and other system resources available to the virtualmachines 332.

Each virtual machine 332 may include a virtual disk 326A-C (generally326) and a virtual processor 328A-C (generally 328.) The virtual disk326, in some embodiments, is a virtualized view of one or more physicaldisks 304 of the virtualization server 301, or a portion of one or morephysical disks 304 of the virtualization server 301. The virtualizedview of the physical disks 304 can be generated, provided, and managedby the hypervisor 302. In some embodiments, hypervisor 302 provides eachvirtual machine 332 with a unique view of the physical disks 304. Thus,in these embodiments, the particular virtual disk 326 included in eachvirtual machine 332 can be unique when compared with the other virtualdisks 326.

A virtual processor 328 can be a virtualized view of one or morephysical processors 308 of the virtualization server 301. In someembodiments, the virtualized view of the physical processors 308 can begenerated, provided, and managed by hypervisor 302. In some embodiments,virtual processor 328 has substantially all of the same characteristicsof at least one physical processor 308. In other embodiments, virtualprocessor 308 provides a modified view of physical processors 308 suchthat at least some of the characteristics of the virtual processor 328are different than the characteristics of the corresponding physicalprocessor 308.

With further reference to FIG. 4, some aspects described herein may beimplemented in a cloud-based environment. FIG. 4 illustrates an exampleof a cloud computing environment (or cloud system) 400. As seen in FIG.4, client computers 411-414 may communicate with a cloud managementserver 410 to access the computing resources (e.g., host servers 403a-403 b (generally referred herein as “host servers 403”), storageresources 404 a-404 b (generally referred herein as “storage resources404”), and network elements 405 a-405 b (generally referred herein as“network resources 405”)) of the cloud system.

Management server 410 may be implemented on one or more physicalservers. The management server 410 may run, for example, Citrix Cloud byCitrix Systems, Inc. of Ft. Lauderdale, Fla., or OPENSTACK, amongothers. Management server 410 may manage various computing resources,including cloud hardware and software resources, for example, hostcomputers 403, data storage devices 404, and networking devices 405. Thecloud hardware and software resources may include private and/or publiccomponents. For example, a cloud may be configured as a private cloud tobe used by one or more particular customers or client computers 411-414and/or over a private network. In other embodiments, public clouds orhybrid public-private clouds may be used by other customers over an openor hybrid networks.

Management server 410 may be configured to provide user interfacesthrough which cloud operators and cloud customers may interact with thecloud system 400. For example, the management server 410 may provide aset of application programming interfaces (APIs) and/or one or morecloud operator console applications (e.g., web-based or standaloneapplications) with user interfaces to allow cloud operators to managethe cloud resources, configure the virtualization layer, manage customeraccounts, and perform other cloud administration tasks. The managementserver 410 also may include a set of APIs and/or one or more customerconsole applications with user interfaces configured to receive cloudcomputing requests from end users via client computers 411-414, forexample, requests to create, modify, or destroy virtual machines withinthe cloud. Client computers 411-414 may connect to management server 410via the Internet or some other communication network, and may requestaccess to one or more of the computing resources managed by managementserver 410. In response to client requests, the management server 410may include a resource manager configured to select and provisionphysical resources in the hardware layer of the cloud system based onthe client requests. For example, the management server 410 andadditional components of the cloud system may be configured toprovision, create, and manage virtual machines and their operatingenvironments (e.g., hypervisors, storage resources, services offered bythe network elements, etc.) for customers at client computers 411-414,over a network (e.g., the Internet), providing customers withcomputational resources, data storage services, networking capabilities,and computer platform and application support. Cloud systems also may beconfigured to provide various specific services, including securitysystems, development environments, user interfaces, and the like.

Certain clients 411-414 may be related, for example, to different clientcomputers creating virtual machines on behalf of the same end user, ordifferent users affiliated with the same company or organization. Inother examples, certain clients 411-414 may be unrelated, such as usersaffiliated with different companies or organizations. For unrelatedclients, information on the virtual machines or storage of any one usermay be hidden from other users.

Referring now to the physical hardware layer of a cloud computingenvironment, availability zones 401-402 (or zones) may refer to acollocated set of physical computing resources. Zones may begeographically separated from other zones in the overall cloud ofcomputing resources. For example, zone 401 may be a first clouddatacenter located in California, and zone 402 may be a second clouddatacenter located in Florida. Management server 410 may be located atone of the availability zones, or at a separate location. Each zone mayinclude an internal network that interfaces with devices that areoutside of the zone, such as the management server 410, through agateway. End users of the cloud (e.g., clients 411-414) might or mightnot be aware of the distinctions between zones. For example, an end usermay request the creation of a virtual machine having a specified amountof memory, processing power, and network capabilities. The managementserver 410 may respond to the user's request and may allocate theresources to create the virtual machine without the user knowing whetherthe virtual machine was created using resources from zone 401 or zone402. In other examples, the cloud system may allow end users to requestthat virtual machines (or other cloud resources) are allocated in aspecific zone or on specific resources 403-405 within a zone.

In this example, each zone 401-402 may include an arrangement of variousphysical hardware components (or computing resources) 403-405, forexample, physical hosting resources (or processing resources), physicalnetwork resources, physical storage resources, switches, and additionalhardware resources that may be used to provide cloud computing servicesto customers. The physical hosting resources in a cloud zone 401-402 mayinclude one or more computer servers 403, such as the virtualizationservers 301 described above, which may be configured to create and hostvirtual machine instances. The physical network resources in a cloudzone 401 or 402 may include one or more network elements 405 (e.g.,network service providers) comprising hardware and/or softwareconfigured to provide a network service to cloud customers, such asfirewalls, network address translators, load balancers, virtual privatenetwork (VPN) gateways, Dynamic Host Configuration Protocol (DHCP)routers, and the like. The storage resources in the cloud zone 401-402may include storage disks (e.g., solid state drives (SSDs), magnetichard disks, etc.) and other storage devices.

The example cloud computing environment shown in FIG. 4 also may includea virtualization layer (e.g., as shown in FIGS. 1-3) with additionalhardware and/or software resources configured to create and managevirtual machines and provide other services to customers using thephysical resources in the cloud. The virtualization layer may includehypervisors, as described above in FIG. 3, along with other componentsto provide network virtualizations, storage virtualizations, etc. Thevirtualization layer may be as a separate layer from the physicalresource layer, or may share some or all of the same hardware and/orsoftware resources with the physical resource layer. For example, thevirtualization layer may include a hypervisor installed in each of thevirtualization servers 403 with the physical computing resources. Knowncloud systems may alternatively be used, e.g., WINDOWS AZURE (MicrosoftCorporation of Redmond Wash.), AMAZON EC2 (Amazon.com Inc. of Seattle,Wash.), IBM BLUE CLOUD (IBM Corporation of Armonk, N.Y.), or others.

Enterprise Mobility Management Architecture

FIG. 5 represents an enterprise mobility technical architecture 500 foruse in a “Bring Your Own Device” (BYOD) environment. The architectureenables a user of a mobile device 502 to both access enterprise orpersonal resources from a mobile device 502 and use the mobile device502 for personal use. The user may access such enterprise resources 504or enterprise services 508 using a mobile device 502 that is purchasedby the user or a mobile device 502 that is provided by the enterprise tothe user. The user may utilize the mobile device 502 for business useonly or for business and personal use. The mobile device 502 may run aniOS operating system, an Android operating system, or the like. Theenterprise may choose to implement policies to manage the mobile device502. The policies may be implemented through a firewall or gateway insuch a way that the mobile device 502 may be identified, secured orsecurity verified, and provided selective or full access to theenterprise resources (e.g., 504 and 508.) The policies may be mobiledevice management policies, mobile application management policies,mobile data management policies, or some combination of mobile device,application, and data management policies. A mobile device 502 that ismanaged through the application of mobile device management policies maybe referred to as an enrolled device.

In some embodiments, the operating system of the mobile device 502 maybe separated into a managed partition 510 and an unmanaged partition512. The managed partition 510 may have policies applied to it to securethe applications running on and data stored in the managed partition510. The applications running on the managed partition 510 may be secureapplications. In other embodiments, all applications may execute inaccordance with a set of one or more policy files received separate fromthe application, and which define one or more security parameters,features, resource restrictions, and/or other access controls that areenforced by the mobile device management system when that application isexecuting on the mobile device 502. By operating in accordance withtheir respective policy file(s), each application may be allowed orrestricted from communications with one or more other applicationsand/or resources, thereby creating a virtual partition. Thus, as usedherein, a partition may refer to a physically partitioned portion ofmemory (physical partition), a logically partitioned portion of memory(logical partition), and/or a virtual partition created as a result ofenforcement of one or more policies and/or policy files across multipleapplications as described herein (virtual partition). Stateddifferently, by enforcing policies on managed applications, thoseapplications may be restricted to only be able to communicate with othermanaged applications and trusted enterprise resources, thereby creatinga virtual partition that is not accessible by unmanaged applications anddevices.

The secure applications may be email applications, web browsingapplications, software-as-a-service (SaaS) access applications, WindowsApplication access applications, and the like. The secure applicationsmay be secure native applications 514, secure remote applications 522executed by a secure application launcher 518, virtualizationapplications 526 executed by a secure application launcher 518, and thelike. The secure native applications 514 may be wrapped by a secureapplication wrapper 520. The secure application wrapper 520 may includeintegrated policies that are executed on the mobile device 502 when thesecure native application 514 is executed on the mobile device 502. Thesecure application wrapper 520 may include meta-data that points thesecure native application 514 running on the mobile device 502 to theresources hosted at the enterprise (e.g., 504 and 508) that the securenative application 514 may require to complete the task requested uponexecution of the secure native application 514. The secure remoteapplications 522 executed by a secure application launcher 518 may beexecuted within the secure application launcher 518. The virtualizationapplications 526 executed by a secure application launcher 518 mayutilize resources on the mobile device 502, at the enterprise resources504, and the like. The resources used on the mobile device 502 by thevirtualization applications 526 executed by a secure applicationlauncher 518 may include user interaction resources, processingresources, and the like. The user interaction resources may be used tocollect and transmit keyboard input, mouse input, camera input, tactileinput, audio input, visual input, gesture input, and the like. Theprocessing resources may be used to present a user interface, processdata received from the enterprise resources 504, and the like. Theresources used at the enterprise resources 504 by the virtualizationapplications 526 executed by a secure application launcher 518 mayinclude user interface generation resources, processing resources, andthe like. The user interface generation resources may be used toassemble a user interface, modify a user interface, refresh a userinterface, and the like. The processing resources may be used to createinformation, read information, update information, delete information,and the like. For example, the virtualization application 526 may recorduser interactions associated with a graphical user interface (GUI) andcommunicate them to a server application where the server applicationwill use the user interaction data as an input to the applicationoperating on the server. In such an arrangement, an enterprise may electto maintain the application on the server side as well as data, files,etc. associated with the application. While an enterprise may elect to“mobilize” some applications in accordance with the principles herein bysecuring them for deployment on the mobile device 502, this arrangementmay also be elected for certain applications. For example, while someapplications may be secured for use on the mobile device 502, othersmight not be prepared or appropriate for deployment on the mobile device502 so the enterprise may elect to provide the mobile user access to theunprepared applications through virtualization techniques. As anotherexample, the enterprise may have large complex applications with largeand complex data sets (e.g., material resource planning applications)where it would be very difficult, or otherwise undesirable, to customizethe application for the mobile device 502 so the enterprise may elect toprovide access to the application through virtualization techniques. Asyet another example, the enterprise may have an application thatmaintains highly secured data (e.g., human resources data, customerdata, engineering data) that may be deemed by the enterprise as toosensitive for even the secured mobile environment so the enterprise mayelect to use virtualization techniques to permit mobile access to suchapplications and data. An enterprise may elect to provide both fullysecured and fully functional applications on the mobile device 502 aswell as a virtualization application 526 to allow access to applicationsthat are deemed more properly operated on the server side. In anembodiment, the virtualization application 526 may store some data,files, etc. on the mobile device 502 in one of the secure storagelocations. An enterprise, for example, may elect to allow certaininformation to be stored on the mobile device 502 while not permittingother information.

In connection with the virtualization application 526, as describedherein, the mobile device 502 may have a virtualization application 526that is designed to present GUIs and then record user interactions withthe GUI. The virtualization application 526 may communicate the userinteractions to the server side to be used by the server sideapplication as user interactions with the application. In response, theapplication on the server side may transmit back to the mobile device502 a new GUI. For example, the new GUI may be a static page, a dynamicpage, an animation, or the like, thereby providing access to remotelylocated resources.

The secure applications 514 may access data stored in a secure datacontainer 528 in the managed partition 510 of the mobile device 502. Thedata secured in the secure data container may be accessed by the securenative applications 514, secure remote applications 522 executed by asecure application launcher 518, virtualization applications 526executed by a secure application launcher 518, and the like. The datastored in the secure data container 528 may include files, databases,and the like. The data stored in the secure data container 528 mayinclude data restricted to a specific secure application 530, sharedamong secure applications 532, and the like. Data restricted to a secureapplication may include secure general data 534 and highly secure data538. Secure general data may use a strong form of encryption such asAdvanced Encryption Standard (AES) 128-bit encryption or the like, whilehighly secure data 538 may use a very strong form of encryption such asAES 256-bit encryption. Data stored in the secure data container 528 maybe deleted from the mobile device 502 upon receipt of a command from thedevice manager 524. The secure applications (e.g., 514, 522, and 526)may have a dual-mode option 540. The dual mode option 540 may presentthe user with an option to operate the secured application in anunsecured or unmanaged mode. In an unsecured or unmanaged mode, thesecure applications may access data stored in an unsecured datacontainer 542 on the unmanaged partition 512 of the mobile device 502.The data stored in an unsecured data container may be personal data 544.The data stored in an unsecured data container 542 may also be accessedby unsecured applications 546 that are running on the unmanagedpartition 512 of the mobile device 502. The data stored in an unsecureddata container 542 may remain on the mobile device 502 when the datastored in the secure data container 528 is deleted from the mobiledevice 502. An enterprise may want to delete from the mobile device 502selected or all data, files, and/or applications owned, licensed orcontrolled by the enterprise (enterprise data) while leaving orotherwise preserving personal data, files, and/or applications owned,licensed or controlled by the user (personal data). This operation maybe referred to as a selective wipe. With the enterprise and personaldata arranged in accordance to the aspects described herein, anenterprise may perform a selective wipe.

The mobile device 502 may connect to enterprise resources 504 andenterprise services 508 at an enterprise, to the public Internet 548,and the like. The mobile device 502 may connect to enterprise resources504 and enterprise services 508 through virtual private networkconnections. The virtual private network connections, also referred toas microVPN or application-specific VPN, may be specific to particularapplications (as illustrated by microVPNs 550, particular devices,particular secured areas on the mobile device (as illustrated by O/S VPN552), and the like. For example, each of the wrapped applications in thesecured area of the mobile device 502 may access enterprise resourcesthrough an application specific VPN such that access to the VPN would begranted based on attributes associated with the application, possibly inconjunction with user or device attribute information. The virtualprivate network connections may carry Microsoft Exchange traffic,Microsoft Active Directory traffic, HyperText Transfer Protocol (HTTP)traffic, HyperText Transfer Protocol Secure (HTTPS) traffic, applicationmanagement traffic, and the like. The virtual private networkconnections may support and enable single-sign-on authenticationprocesses 554. The single-sign-on processes may allow a user to providea single set of authentication credentials, which are then verified byan authentication service 558. The authentication service 558 may thengrant to the user access to multiple enterprise resources 504, withoutrequiring the user to provide authentication credentials to eachindividual enterprise resource 504.

The virtual private network connections may be established and managedby an access gateway 560. The access gateway 560 may include performanceenhancement features that manage, accelerate, and improve the deliveryof enterprise resources 504 to the mobile device 502. The access gateway560 may also re-route traffic from the mobile device 502 to the publicInternet 548, enabling the mobile device 502 to access publiclyavailable and unsecured applications that run on the public Internet548. The mobile device 502 may connect to the access gateway via atransport network 562. The transport network 562 may use one or moretransport protocols and may be a wired network, wireless network, cloudnetwork, local area network, metropolitan area network, wide areanetwork, public network, private network, and the like.

The enterprise resources 504 may include email servers, file sharingservers, SaaS applications, Web application servers, Windows applicationservers, and the like. Email servers may include Exchange servers, LotusNotes servers, and the like. File sharing servers may include ShareFileservers, and the like. SaaS applications may include Salesforce, and thelike. Windows application servers may include any application serverthat is built to provide applications that are intended to run on alocal Windows operating system, and the like. The enterprise resources504 may be premise-based resources, cloud-based resources, and the like.The enterprise resources 504 may be accessed by the mobile device 502directly or through the access gateway 560. The enterprise resources 504may be accessed by the mobile device 502 via the transport network 562.

The enterprise services 508 may include authentication services 558,threat detection services 564, device manager services 524, file sharingservices 568, policy manager services 570, social integration services572, application controller services 574, and the like. Authenticationservices 558 may include user authentication services, deviceauthentication services, application authentication services, dataauthentication services, and the like. Authentication services 558 mayuse certificates. The certificates may be stored on the mobile device502, by the enterprise resources 504, and the like. The certificatesstored on the mobile device 502 may be stored in an encrypted locationon the mobile device 502, the certificate may be temporarily stored onthe mobile device 502 for use at the time of authentication, and thelike. Threat detection services 564 may include intrusion detectionservices, unauthorized access attempt detection services, and the like.Unauthorized access attempt detection services may include unauthorizedattempts to access devices, applications, data, and the like. Devicemanagement services 524 may include configuration, provisioning,security, support, monitoring, reporting, and decommissioning services.File sharing services 568 may include file management services, filestorage services, file collaboration services, and the like. Policymanager services 570 may include device policy manager services,application policy manager services, data policy manager services, andthe like. Social integration services 572 may include contactintegration services, collaboration services, integration with socialnetworks such as Facebook, Twitter, and LinkedIn, and the like.Application controller services 574 may include management services,provisioning services, deployment services, assignment services,revocation services, wrapping services, and the like.

The enterprise mobility technical architecture 500 may include anapplication store 578. The application store 578 may include unwrappedapplications 580, pre-wrapped applications 582, and the like.Applications may be populated in the application store 578 from theapplication controller 574. The application store 578 may be accessed bythe mobile device 502 through the access gateway 560, through the publicInternet 548, or the like. The application store 578 may be providedwith an intuitive and easy to use user interface.

A software development kit 584 may provide a user the capability tosecure applications selected by the user by wrapping the application asdescribed previously in this description. An application that has beenwrapped using the software development kit 584 may then be madeavailable to the mobile device 502 by populating it in the applicationstore 578 using the application controller 574.

The enterprise mobility technical architecture 500 may include amanagement and analytics capability 588. The management and analyticscapability 588 may provide information related to how resources areused, how often resources are used, and the like. Resources may includedevices, applications, data, and the like. How resources are used mayinclude which devices download which applications, which applicationsaccess which data, and the like. How often resources are used mayinclude how often an application has been downloaded, how many times aspecific set of data has been accessed by an application, and the like.

FIG. 6 is another illustrative enterprise mobility management system600. Some of the components of the mobility management system 500described above with reference to FIG. 5 have been omitted for the sakeof simplicity. The architecture of the system 600 depicted in FIG. 6 issimilar in many respects to the architecture of the system 500 describedabove with reference to FIG. 5 and may include additional features notmentioned above.

In this case, the left hand side represents an enrolled mobile device602 with a client agent 604, which interacts with gateway server 606(which includes Access Gateway and application controller functionality)to access various enterprise resources 608 and services 609 such asExchange, Sharepoint, public-key infrastructure (PKI) Resources,Kerberos Resources, Certificate Issuance service, as shown on the righthand side above. Although not specifically shown, the mobile device 602may also interact with an enterprise application store (StoreFront) forthe selection and downloading of applications.

The client agent 604 acts as the UI (user interface) intermediary forWindows apps/desktops hosted in an Enterprise data center, which areaccessed using the High-Definition User Experience (HDX)/ICA displayremoting protocol. The client agent 604 also supports the installationand management of native applications on the mobile device 602, such asnative iOS or Android applications. For example, the managedapplications 610 (mail, browser, wrapped application) shown in thefigure above are all native applications that execute locally on themobile device 602. Client agent 604 and application management frameworkof this architecture act to provide policy driven managementcapabilities and features such as connectivity and SSO (single sign on)to enterprise resources/services 608. The client agent 604 handlesprimary user authentication to the enterprise, normally to AccessGateway (AG) 606 with SSO to other gateway server components. The clientagent 604 obtains policies from gateway server 606 to control thebehavior of the managed applications 610 on the mobile device 602.

The Secure InterProcess Communication (IPC) links 612 between the nativeapplications 610 and client agent 604 represent a management channel,which may allow a client agent to supply policies to be enforced by theapplication management framework 614 “wrapping” each application. TheIPC channel 612 may also allow client agent 604 to supply credential andauthentication information that enables connectivity and SSO toenterprise resources 608. Finally, the IPC channel 612 may allow theapplication management framework 614 to invoke user interface functionsimplemented by client agent 604, such as online and offlineauthentication.

Communications between the client agent 604 and gateway server 606 areessentially an extension of the management channel from the applicationmanagement framework 614 wrapping each native managed application 610.The application management framework 614 may request policy informationfrom client agent 604, which in turn may request it from gateway server606. The application management framework 614 may requestauthentication, and client agent 604 may log into the gateway servicespart of gateway server 606 (for example, Citrix Gateway). Client agent604 may also call supporting services on gateway server 606, which mayproduce input material to derive encryption keys for the local datavaults 616, or may provide client certificates which may enable directauthentication to PKI protected resources, as more fully explainedbelow.

In more detail, the application management framework 614 “wraps” eachmanaged application 610. This may be incorporated via an explicit buildstep, or via a post-build processing step. The application managementframework 614 may “pair” with client agent 604 on first launch of anapplication 610 to initialize the Secure IPC channel 612 and obtain thepolicy for that application. The application management framework 614may enforce relevant portions of the policy that apply locally, such asthe client agent login dependencies and some of the containment policiesthat restrict how local OS services may be used, or how they mayinteract with the managed application 610.

The application management framework 614 may use services provided byclient agent 604 over the Secure IPC channel 612 to facilitateauthentication and internal network access. Key management for theprivate and shared data vaults 616 (containers) may be also managed byappropriate interactions between the managed applications 610 and clientagent 604. Vaults 616 may be available only after online authentication,or may be made available after offline authentication if allowed bypolicy. First use of vaults 616 may require online authentication, andoffline access may be limited to at most the policy refresh periodbefore online authentication is again required.

Network access to internal resources may occur directly from individualmanaged applications 610 through Access Gateway 606. The applicationmanagement framework 614 may be responsible for orchestrating thenetwork access on behalf of each managed application 610. Client agent604 may facilitate these network connections by providing suitable timelimited secondary credentials obtained following online authentication.Multiple modes of network connection may be used, such as reverse webproxy connections and end-to-end VPN-style tunnels 618.

The Mail and Browser managed applications 610 have special status andmay make use of facilities that might not be generally available toarbitrary wrapped applications. For example, the Mail application 610may use a special background network access mechanism that allows it toaccess an Exchange server 608 over an extended period of time withoutrequiring a full AG logon. The Browser application 610 may use multipleprivate data vaults 616 to segregate different kinds of data.

This architecture may support the incorporation of various othersecurity features. For example, gateway server 606 (including itsgateway services) in some cases may not need to validate activedirectory (AD) passwords. It can be left to the discretion of anenterprise whether an AD password may be used as an authenticationfactor for some users in some situations. Different authenticationmethods may be used if a user is online or offline (i.e., connected ornot connected to a network).

Step up authentication is a feature wherein gateway server 606 mayidentify managed native applications 610 that are allowed to have accessto highly classified data requiring strong authentication, and ensurethat access to these applications is only permitted after performingappropriate authentication, even if this means a re-authentication isrequired by the user after a prior weaker level of login.

Another security feature of this solution is the encryption of the datavaults 616 (containers) on the mobile device 602. The vaults 616 may beencrypted so that all on-device data including files, databases, andconfigurations are protected. For on-line vaults, the keys may be storedon the server (gateway server 606), and for off-line vaults, a localcopy of the keys may be protected by a user password or biometricvalidation. If or when data is stored locally on the mobile device 602in the secure container 616, it may be preferred that a minimum of AES256 encryption algorithm be utilized.

Other secure container features may also be implemented. For example, alogging feature may be included, wherein security events happeninginside a managed application 610 may be logged and reported to thebackend. Data wiping may be supported, such as if or when the managedapplication 610 detects tampering, associated encryption keys may bewritten over with random data, leaving no hint on the file system thatuser data was destroyed. Screenshot protection may be another feature,where an application may prevent any data from being stored inscreenshots. For example, the key window's hidden property may be set toYES. This may cause whatever content is currently displayed on thescreen to be hidden, resulting in a blank screenshot where any contentwould normally reside.

Local data transfer may be prevented, such as by preventing any datafrom being locally transferred outside the application container, e.g.,by copying it or sending it to an external application. A keyboard cachefeature may operate to disable the autocorrect functionality forsensitive text fields. SSL certificate validation may be operable so theapplication specifically validates the server SSL certificate instead ofit being stored in the keychain. An encryption key generation featuremay be used such that the key used to encrypt data on the mobile device602 is generated using a passphrase or biometric data supplied by theuser (if offline access is required). It may be XORed with another keyrandomly generated and stored on the server side if offline access isnot required. Key Derivation functions may operate such that keysgenerated from the user password use KDFs (key derivation functions,notably Password-Based Key Derivation Function 2 (PBKDF2)) rather thancreating a cryptographic hash of it. The latter makes a key susceptibleto brute force or dictionary attacks.

Further, one or more initialization vectors may be used in encryptionmethods. An initialization vector will cause multiple copies of the sameencrypted data to yield different cipher text output, preventing bothreplay and cryptanalytic attacks. This will also prevent an attackerfrom decrypting any data even with a stolen encryption key. Further,authentication then decryption may be used, wherein application data isdecrypted only after the user has authenticated within the application.Another feature may relate to sensitive data in memory, which may bekept in memory (and not in disk) only when it's needed. For example,login credentials may be wiped from memory after login, and encryptionkeys and other data inside objective-C instance variables are notstored, as they may be easily referenced. Instead, memory may bemanually allocated for these.

An inactivity timeout may be implemented, wherein after a policy-definedperiod of inactivity, a user session is terminated.

Data leakage from the application management framework 614 may beprevented in other ways. For example, if or when a managed application610 is put in the background, the memory may be cleared after apredetermined (configurable) time period. When backgrounded, a snapshotmay be taken of the last displayed screen of the application to fastenthe foregrounding process. The screenshot may contain confidential dataand hence should be cleared.

Another security feature may relate to the use of an OTP (one timepassword) 620 without the use of an AD (active directory) 622 passwordfor access to one or more applications. In some cases, some users do notknow (or are not permitted to know) their AD password, so these usersmay authenticate using an OTP 620 such as by using a hardware OTP systemlike SecurID (OTPs may be provided by different vendors also, such asEntrust or Gemalto). In some cases, after a user authenticates with auser ID, a text may be sent to the user with an OTP 620. In some cases,this may be implemented only for online use, with a prompt being asingle field.

An offline password may be implemented for offline authentication forthose managed applications 610 for which offline use is permitted viaenterprise policy. For example, an enterprise may want StoreFront to beaccessed in this manner. In this case, the client agent 604 may requirethe user to set a custom offline password and the AD password is notused. Gateway server 606 may provide policies to control and enforcepassword standards with respect to the minimum length, character classcomposition, and age of passwords, such as described by the standardWindows Server password complexity requirements, although theserequirements may be modified.

Another feature may relate to the enablement of a client sidecertificate for certain applications 610 as secondary credentials (forthe purpose of accessing PKI protected web resources via the applicationmanagement framework micro VPN feature). For example, a managedapplication 610 may utilize such a certificate. In this case,certificate-based authentication using ActiveSync protocol may besupported, wherein a certificate from the client agent 604 may beretrieved by gateway server 606 and used in a keychain. Each managedapplication 610 may have one associated client certificate, identifiedby a label that is defined in gateway server 606.

Gateway server 606 may interact with an enterprise special purpose webservice to support the issuance of client certificates to allow relevantmanaged applications to authenticate to internal PKI protectedresources.

The client agent 604 and the application management framework 614 may beenhanced to support obtaining and using client certificates forauthentication to internal PKI protected network resources. More thanone certificate may be supported, such as to match various levels ofsecurity and/or separation requirements. The certificates may be used bythe Mail and Browser managed applications 610, and ultimately byarbitrary wrapped applications 610 (provided those applications use webservice style communication patterns where it is reasonable for theapplication management framework to mediate HTTPS requests).

Application management client certificate support on iOS may rely onimporting a public-key cryptography standards (PKCS) 12 BLOB (BinaryLarge Object) into the iOS keychain in each managed application 610 foreach period of use. Application management framework client certificatesupport may use a HTTPS implementation with private in-memory keystorage. The client certificate may not be present in the iOS keychainand may not be persisted except potentially in “online-only” data valuethat is strongly protected.

Mutual SSL or TLS may also be implemented to provide additional securityby requiring that a mobile device 602 is authenticated to theenterprise, and vice versa. Virtual smart cards for authentication togateway server 606 may also be implemented.

Another feature may relate to application container locking and wiping,which may automatically occur upon jail-break or rooting detections, andoccur as a pushed command from administration console, and may include aremote wipe functionality even when a managed application 610 is notrunning.

A multi-site architecture or configuration of enterprise applicationstore and an application controller may be supported that allows usersto be serviced from one of several different locations in case offailure.

In some cases, managed applications 610 may be allowed to access acertificate and private key via an API (for example, OpenSSL). Trustedmanaged applications 610 of an enterprise may be allowed to performspecific Public Key operations with an application's client certificateand private key. Various use cases may be identified and treatedaccordingly, such as if or when an application behaves like a browserand no certificate access is required, if or when an application reads acertificate for “who am I,” if or when an application uses thecertificate to build a secure session token, and if or when anapplication uses private keys for digital signing of important data(e.g. transaction log) or for temporary data encryption.

Content Resolution Adjustment

FIG. 7 depicts an illustrative system architecture 700 comprising asmall-screen device 702 (e.g., mobile phone, smartphone, personaldigital assistant (PDA), notebook, iPod Touch, client device 107,terminal 240, etc.) and a passive magnifying device 716 (e.g., a screenmagnifier). A screen 704 of the small-screen device 702 may have a sizecomprising a height, a width, and a diagonal. The screen 704 of thesmall-screen device 702 may have a maximum screen resolution and amaximum Pixels Per Inch (PPI), both depending on the manufacture. Thesize, the maximum screen resolution, and the maximum PPI of thesmall-screen device screen 704 may be retrieved from a small-screendevice 702 system information file. The size, the maximum screenresolution, and the maximum PPI of the small-screen device screen 704may be additionally, or alternatively, revised or input by a user on thesmall-screen device 702.

A front-facing camera 706 of the small-screen device 702 may captureimages of a screen 712 of the passive magnifying device 716. Thesmall-screen device 702 may detect sizes of the passive magnifyingdevice screen 712 in the captured images. The small-screen device 702may then calculate a distance between the small-screen device screen 704and the passive magnifying device screen 712 based on the detected sizesof the passive magnifying device screen 712 in the captured images. Thesmall-screen device 702 may further comprise proximity, ultrasonic,and/or laser sensors that may be used to measure the distance betweenthe small-screen device screen 704 and the passive magnifying devicescreen 712. The distance between the small-screen device screen 704 andthe passive magnifying device screen 712 may be additionally, oralternatively, input by a user on the small-screen device 702.

The passive magnifying device 716 comprises a stand 710 and the passivemagnifying device screen 712. The stand 710 may provide support forplacing the small-screen device 702. The stand 710 may be adjustable tobe inclined in different angles. The stand 710 may be adjustable to beat different distances from the passive magnifying device screen 712.Different angles of incline and different distances from the passivemagnifying device screen 712 may bring different viewing experiences onthe passive magnifying device screen 712.

The passive magnifying device screen 712 may be an optical magnifyinglens (e.g., a Fresnel lens). The passive magnifying device screen 712(e.g., the Fresnel lens) may have a focal length. The passive magnifyingdevice screen 712 may have a size comprising a height, a width, and adiagonal. The passive magnifying device screen 712 may have a preferredview screen resolution. Because the passive magnifying device screen 712only magnifies the small-screen device screen 704 passively, the passivemagnifying device screen 712 may not have a screen resolution dependingon the manufacture. The preferred view screen resolution of the passivemagnifying device screen 712 may be a recommended screen resolution thatmay bring the optimal viewing experience on the passive magnifyingdevice screen 712. The focal length, the size, and the preferred viewscreen resolution of the passive magnifying device screen 712 may beinput by a user on the small-screen device 702.

Content may be output on the small-screen device screen 704 and may bemagnified on the passive magnifying device screen 712. Content may bedesktops, applications, Word documents, PowerPoint presentations, Excelsheets, emails, messages, webpages, photos, videos, etc. Content may beoutput by the small-screen device 702. Content may additionally, oralternatively, be output on the small-screen device 702 from aremote-access system, a virtualized system, a cloud-based system, and/oran enterprise mobility management system. For example, content may beoutput on the small-screen device 702 from a hypervisor developed byCitrix Systems, a Citrix remote desktop and applications, a CitrixCloud, etc. When content is output from other than the small-screendevice 702, a resolution of the content on the small-screen device 702may be affected by a bandwidth, a data transmission speed, etc., of aconnection with an original data source. The resolution may not beoptimal for the small-screen device screen 704 or the passive magnifyingdevice screen 712. The resolution may be adjusted to achieve thepreferred view resolution on the passive magnifying device screen 712.

For example, an image 708 may be output on the small-screen device 702in a first resolution. The image 708 may be magnified to be viewed asimage 714 on the passive magnifying device screen 712. A magnificationratio of the passive magnifying device screen 712 may be calculated asthe ratio of a size of an object on the passive magnifying device screen712 to the size of the object on the small-screen device screen 704. Themagnification ratio may depend on the distance between the small-screendevice screen 704 and the passive magnifying device screen 712. Theresolution of the image 714 may depend on the magnification ratio. Forthe image 714 to be in the preferred view resolution, the image 708 mayneed to be output on the small-screen device screen 704 in a secondresolution different from the first resolution. The second resolutionmay be determined based on the magnification ratio and the size of thepassive magnifying device screen 712.

In some aspects, the small-screen device 702 may receive the contentfrom a remote computing device in the first resolution and in the secondresolution. In some aspects, the second resolution may exceed themaximum screen resolution of the small-screen device screen 704. In thatcase, the content may have to be output in the maximum screen resolutionon the small-screen device screen 704, instead of in the determinedsecond resolution. In some aspects, the second resolution may exceed themaximum PPI of the small-screen device screen 704. In that case, a thirdresolution may be determined based on the maximum PPI, and the contentmay have to be output in the third resolution on the small-screen devicescreen 704, instead of in the determined second resolution.

FIG. 8 depicts an illustrative optical magnification mechanism 800 for apassive magnifying device and an illustrative projection mechanism for aprojector. Similar to system 700, the optical magnification mechanism800 may comprise a small-screen device screen 802, and a passivemagnifying device screen 804 (e.g., a Fresnel lens). A magnificationratio of the passive magnifying device screen 804 may be based on adistance 806 between the small-screen device screen 802 and the passivemagnifying device screen 804, and a focal length 808 of the passivemagnifying device screen 804 (e.g., the Fresnel lens).

A mathematical formula for calculating the magnification ratio may be:

${{Magnification}\mspace{14mu}{Ratio}} = \frac{808\mspace{14mu}{Focal}\mspace{14mu}{Length}}{{808\mspace{14mu}{Focal}\mspace{14mu}{Length}} - {806\mspace{14mu}{Distance}}}$

The projection mechanism may comprise a projector lens 814, a projectoraperture width 820, a projector focal length 818, and a screen 812. Asize 822 of a projected content on the screen 812 may be based on aprojection distance 816, and specifications (e.g., the aperture width820, the focal length 818) of the projector.

A mathematical formula for calculating the size 822 of the projectedcontent on the screen 812 may be:

${822\mspace{14mu}{Projected}\mspace{14mu}{Size}} = {\frac{{816\mspace{14mu}{Projection}\mspace{14mu}{Length}} - {818\mspace{14mu}{Focal}\mspace{14mu}{Length}}}{818\mspace{14mu}{Focal}\mspace{14mu}{Length}} \times 820\mspace{14mu}{Aperture}}$

FIG. 9 depicts illustrative screenshots used to determine distance 806with a captured image. Referring to FIG. 7, the front-facing camera 706of the small-screen device 702 may capture an image of the passivemagnifying device screen 712. When the distance between the small-screendevice screen 704 and the passive magnifying device screen 712 issmaller, the captured image of the passive magnifying device screen 712may be bigger. When the distance between the small-screen device screen704 and the passive magnifying device screen 712 is greater, thecaptured image of the passive magnifying device screen 712 may besmaller.

When the distance between the small-screen device screen 704 and thepassive magnifying device screen 712 is at a known reference distance,the front-facing camera 706 of the small-screen device 702 may capture areference image of the passive magnifying device screen 712. In FIG. 9reference image, 902 is the small-screen device, 904 is the small-screendevice screen, 906 is the front-facing camera, 908 is the edge of thecaptured photo, 910 is the captured image (i.e., the reference image) ofthe passive magnifying device screen 712, and 912 is the reference widthof the passive magnifying device screen 712 in the reference image 910.

When the distance between the small-screen device screen 704 and thepassive magnifying device screen 712 is at an unknown distance to bemeasured, the front-facing camera 706 of the small-screen device 702 maycapture an image of the passive magnifying device screen 712. In FIG. 9captured image, 914 is the captured width of the passive magnifyingdevice screen 712 in the captured image.

A mathematical formula for calculating the measured distance may be:

${806\mspace{14mu}{Distance}} = {{Reference}\mspace{14mu}{Distance} \times \frac{912\mspace{14mu}{Reference}\mspace{14mu}{Width}}{914\mspace{14mu}{Captured}\mspace{14mu}{Width}} \times {Scaling}\mspace{14mu}{Factor}}$

The scaling factor may be used to calibrate the mathematical formula sothat the measured distance may be accurate.

FIG. 10 depicts illustrative screenshots that may be used whendetermining system parameters for the small-screen device screen 704 andthe passive magnifying device screen 712. The system parameters may beused in adjusting the content resolution.

The small-screen device screen 704 may have a size comprising a height,a width, and a diagonal. The small-screen device screen 704 may have amaximum screen resolution and a maximum PPI, both depending on themanufacture. The size, the maximum screen resolution, and the maximumPPI of the small-screen device screen 704 may be retrieved from thesmall-screen device 702 system information file. The size, the maximumscreen resolution, and the maximum PPI of the small-screen device screen704 may be additionally, or alternatively, revised or input by a user onthe small-screen device 702.

For example, in FIG. 10 mobile device system information, 1002 is thesmall-screen device, 1004 is the small-screen device screen, 1006 is amessage comprising detailed maximum screen resolution data, maximum PPIdata, and screen size data. The message may be generated by thesmall-screen device 1002 after retrieving the system parameters from thesmall-screen device 1002 system information file. If all the systemparameters are correct, a user may confirm the system parameters byhitting the confirm button 1008. If some system parameters areincorrect, a user may revise the erroneous system parameters by hittingthe revise button 1010. A user may also directly input the systemparameters data on the small-screen device screen 1004.

The passive magnifying device screen 712 (e.g., the Fresnel lens) mayhave a focal length. The passive magnifying device screen 712 may have asize comprising a height, a width, and a diagonal. The passivemagnifying device screen 712 may have a preferred view screenresolution. The preferred view screen resolution of the passivemagnifying device screen 712 is a recommended screen resolution that maybring the optimal viewing experience on the passive magnifying devicescreen 712. The focal length, the size, and the preferred view screenresolution of the passive magnifying device screen 712 may be input by auser on the small-screen device 702.

For example, in FIG. 10 passive magnifying device system information,the small-screen device 1002 may generate input forms to collect passivemagnifying device system information. The input forms may also begenerated by a content resolution adjustment application. 1012, 1016,and 1018 may ask the user to input the focal length, the preferred viewscreen resolution, and the screen size, respectively. The user may inputthe system parameters by hitting the enter buttons 1014, 1018, and 1022.

FIG. 11 depicts an illustrative system architecture 1100 comprising asmall-screen device 1102 (e.g., mobile phone, smartphone, personaldigital assistant (PDA), notebook, iPod Touch, client device 107,terminal 240, etc.), a projector 1106 (e.g., a built-in mobile phoneprojector, a wireless projector, etc.), and a screen 1110 (e.g., aprojector screen, a wall, an object, etc.). The system parameters of thesmall-screen device screen 1104 in system 1100 may be the same as thesystem parameters of the small-screen device screen 704 in system 700.The small-screen device 1102 may retrieve the system parameters of thesmall-screen device screen 1104 from a small-screen device 1102 systeminformation file, similarly like in FIG. 10 mobile device systeminformation.

Content output on the small-screen device 1102 in system 1100 may be thesame as the content output on the small-screen device 702 in system 700.The content may also be output on the small-screen device 1102 from aremote-access system, a virtualized system, a cloud-based system, and/oran enterprise mobility management system. For example, the content maybe output on the small-screen device 1102 from a hypervisor developed byCitrix Systems, a Citrix remote desktop and applications, a CitrixCloud, etc. When the content is output from other than the small-screendevice 1102, a resolution of the content on the small-screen device 1102may be affected by a bandwidth or a data transmission speed etc., of aconnection with an original data source. The resolution may not beoptimal for the small-screen device screen 1104 or the screen 1110 afterthe content is projected by the projector 1106. The content resolutionon the small-screen device screen 1104 may be adjusted to match thepreferred view screen resolution on the screen 1110. The screen 1110 maybe a passive receiving medium such as a projector screen, a wall, anobject, etc. Therefore, there may be no screen resolution based onmanufacture. However, there may be a preferred view screen resolutionbased on a size of the projected content. The preferred view screenresolution may bring the optimal viewing experience of the content onthe screen 1110.

The projector 1106 may be a component of the small-screen device 1102.The projector 1106 may be a separate and independent entity from thesmall-screen device 1102. A separate projector 1106 may be connected tothe small-screen device 1102 with a cable such as a USB cable, etc., orwirelessly such as blue tooth, etc. Once connected, the separateprojector 1106 may project the content output on the small-screen device1102 onto the screen 1110, similarly like a built-in projector 1106.

The screen 1110 may be a screen, a wall, an object, etc. that a viewermay prefer to view the content on. Because the screen 1110 is a passivereceiving medium of the projected images, the screen 1110 may not have amanufactured screen resolution. However, the screen 1110 may have apreferred view resolution that may bring the optimal viewing experienceon the screen 1110. The screen 1110 may have a size (e.g., a height, awidth and a diagonal of a projector screen). If the screen 1110 is awall or an object that may not have an easily definable size, the screen1110 may have a preferred view size, an arbitrary size that may bringthe optimal viewing experience on the screen 1110. For example, a usermay want an entire content item to be projected on the screen 1110instead of having a part of the content item to be outside a boundary ofthe screen 1110.

The projector 1106 may have a projection distance 1114. The size of theprojected content may depend on the projection distance 1114 andspecifications (e.g., the aperture width, the focal length, etc.) of theprojector 1106. For a given projector 1106, the longer the projectiondistance 1114, the greater the size of the projected content may be. Theshorter the projection distance 1114, the smaller the size of theprojected content may be.

A mathematical formula for calculating the size of the projected contentfor the projector 1106 may be:

${822\mspace{14mu}{Projected}\mspace{14mu}{Size}} = {\frac{{816\mspace{14mu}{Projection}\mspace{14mu}{Length}} - {818\mspace{14mu}{Focal}\mspace{14mu}{Length}}}{818\mspace{14mu}{Focal}\mspace{14mu}{Length}} \times 820\mspace{14mu}{Aperture}}$

The projector 1106 may have a maximum projection length. The maximumprojection length may depend on the brightness of the projector 1106such as in lumens. The maximum projection length may be affected by thedarkness of the viewing environment. In a darker environment, aprojector 1106 with a predetermined brightness may project farther thanin a lighter environment. The maximum projection length may limit theprojection distance 1114.

The maximum projection length of the projector 1106, the preferred viewscreen size, the preferred view screen resolution, and thespecifications (e.g., the aperture width, the focal length, etc.) of theprojector 1106 may be input by a user on the small-screen device 1102,similarly like in FIG. 10 passive magnifying device system information.

The projection distance 1114 may be measured by a proximity, ultrasonic,and/or laser sensor on the small-screen device 1102. The projectiondistance 1114 may be input by a user on the small-screen device 1102.The projection distance 1114 may also be determined in a similar way asshown in FIG. 9. The captured image may be of a projector screen. Whenthe distance between the projector 1106 and the projector screen issmaller, the captured image of the projector screen may be bigger. Whenthe distance between the projector 1106 and the projector screen isgreater, the captured image of the projector screen may be smaller. Thecaptured image may be captured by a front-facing or rear-facing cameraof the small-screen device 1102.

When the screen 1110 is a wall or an object that may not have a sizethat may be easily captured, the projector 1106 may project a virtualruler onto the screen 1110. A front-facing or rear-facing camera of thesmall-screen device 1102 may capture an image of the projected virtualruler. The small-screen device 1102 may then detect a virtual rulerlength in the captured image. The projection distance 1114 may becalculated based on the detected virtual ruler length in the capturedimage, a reference distance, and a reference virtual ruler length in areference image. The reference image may be captured with projector 1106placed at the reference distance from the screen 1110.

A mathematical formula for calculating the projection distance 1114based on the projected virtual ruler may be:

${1114\mspace{14mu}{Distance}} = {{Reference}\mspace{14mu}{Distance} \times \frac{{Reference}\mspace{14mu}{Ruler}\mspace{14mu}{Size}}{{Captured}\mspace{14mu}{Ruler}\mspace{14mu}{Size}} \times {Scaling}\mspace{14mu}{Factor}}$

The scaling factor may be used to calibrate the mathematical formula sothat the calculated projection distance 1114 may be accurate.

As an example, an image 1108 may be output on the small-screen device1102 in a first resolution. The image 1108 may be projected by theprojector 1106 to be viewed as image 1112 on the screen 1110. The sizeof the projected content may depend on the projection distance 1114between the projector 1106 and the screen 1110, and the specifications(e.g., the aperture width, the focal length, etc.) of the projector1106. Once the size of the projected content is calculated, a user maydetermine a preferred view screen resolution. For example, if the sizeof the projected content is greater, the user may prefer a higher screenresolution. For the image 1112 to be in the preferred view screenresolution, the image 1108 may need to be output on the small-screendevice screen 1104 in a second resolution different from the firstresolution. The second resolution may be determined by matching thepreferred view screen resolution on the screen 1110.

In some aspects, the small-screen device 1102 may receive the contentfrom a remote computing device in the first resolution and in the secondresolution. In some aspects, the second resolution may exceed themaximum screen resolution of the small-screen device screen 1104. Inthat case, the content may have to be output in the maximum screenresolution on the small-screen device screen 1104, instead of in thedetermined second resolution. In some aspects, the second resolution mayexceed the maximum PPI of the small-screen device screen 1104. In thatcase, a third resolution may be determined based on the maximum PPI, andthe content may have to be output in the third resolution on thesmall-screen device screen 1104, instead of in the determined secondresolution.

FIG. 12 is a flow chart showing a method 1200 of content resolutionadjustment comprising a small-screen device (e.g., a small-screen device702) and a passive magnifying device (e.g., a passive magnifying device712).

At 1202, the small-screen device 702 may output content on thesmall-screen device screen 704. The content may be output in a firstresolution. The content may be output by the small-screen device 702.Additionally, or alternatively, the content may be output on thesmall-screen device 702 from a remote computing device. The remotecomputing device may be from a remote-access system, a virtualizedsystem, a cloud-based system, and/or an enterprise mobility managementsystem. For example, the content may be output on the small-screendevice 702 from a hypervisor developed by Citrix Systems, a Citrixremote desktop and applications, a Citrix Cloud, etc. When the contentis output from other than the small-screen device 702, the firstresolution of the content on the small-screen device 702 may be affectedby a bandwidth or a data transmission speed etc., of a connection withan original data source.

At 1204, the small-screen device 702 may determine a maximum screenresolution, a maximum PPI, and a screen size of the small-screen devicescreen 704. The maximum screen resolution, the maximum PPI, and thescreen size of the small-screen device screen 704 may be retrieved froma small-screen device 702 system information file, such as shown in FIG.10 mobile device system information. The maximum screen resolution, themaximum PPI, and the screen size of the small-screen device screen 704may be used to adjust the content resolution.

At 1206, the small-screen device 702 may determine a focal length, apreferred view screen resolution, and a screen size of the passivemagnifying device screen 712. The preferred view screen resolution is arecommended screen resolution for the optimal viewing experience on thepassive magnifying device screen 712. The focal length, the preferredview screen resolution, and the screen size of the passive magnifyingdevice screen 712 may be input by a user on the small-screen device 702,such as shown in FIG. 10 passive magnifying device system information.The focal length may be used to calculate a magnification ratio. Thepreferred view screen resolution, and the screen size of the passivemagnifying device screen 712 may be used to adjust the contentresolution.

At 1208, the small-screen device 702 may determine a distance betweenthe small-screen device screen 704 and the passive magnifying devicescreen 712. Additionally, or alternatively, the distance between thesmall-screen device screen 704 and the passive magnifying device screen712 may be input by a user on the small-screen device 702. Themeasurement of the distance may be made by a proximity, ultrasonic,and/or laser sensor on the small-screen device 702. The measurement ofthe distance may be made by a front-facing camera 706 of thesmall-screen device 702. The front-facing camera 706 of the small-screendevice 702 may capture an image of the passive magnifying device screen712. Based on the size of the passive magnifying device screen 712 inthe captured image and a reference size of the passive magnifying devicescreen 712 in a reference image (e.g., reference image 910), thedistance between the small-screen device screen 704 and the passivemagnifying device screen 712 may be calculated. A detailed method isshown in FIG. 9. A mathematical formula for calculating the measureddistance between the small-screen device screen 704 and the passivemagnifying device screen 712 may be:

${806\mspace{14mu}{Distance}} = {{Reference}\mspace{14mu}{Distance} \times \frac{912\mspace{14mu}{Reference}\mspace{14mu}{Width}}{914\mspace{14mu}{Captured}\mspace{14mu}{Width}} \times {Scaling}\mspace{14mu}{Factor}}$

At 1210, the small-screen device 702 may calculate a magnification ratiobased on the passive magnifying device 716 focal length and the measureddistance 806. A magnification ratio for the passive magnifying device716 may be calculated as the ratio of a size of an object on the passivemagnifying device screen 712 to the size of the object on thesmall-screen device screen 704. The passive magnifying device screen 712may be an optical magnifying lens (e.g., a Fresnel lens). A detailedoptical magnification mechanism 800 is shown in FIG. 8. A mathematicalformula for calculating the magnification ratio may be:

${{Magnification}\mspace{14mu}{Ratio}} = \frac{808\mspace{14mu}{Focal}\mspace{14mu}{Length}}{{808\mspace{14mu}{Focal}\mspace{14mu}{Length}} - {806\mspace{14mu}{Distance}}}$

At 1212, the small-screen device 702 may adjust the content on thesmall-screen device screen 704 to a second resolution. The content maybe adjusted to be output in the second resolution by the small-screendevice 702. The content in the second resolution may additionally, oralternatively, be requested from a remote computing device. The secondresolution may provide the preferred view screen resolution of thecontent on the passive magnifying device screen 712. The secondresolution may be determined based on a series of mathematical formulas.

${2{nd}\mspace{14mu}{PPI}} = {{Magnification}{\mspace{11mu}\;}{Ratio} \times \frac{\sqrt{{{Preferred}\mspace{14mu}{Width}^{2}} + {{Preferred}\mspace{14mu}{Height}^{2}}}}{{Diagonal}\mspace{14mu}{Screen}\mspace{14mu}{Size}\mspace{14mu}{of}\mspace{14mu}{Passive}\mspace{14mu}{Display}\mspace{14mu}{Device}}}$${2{nd}\mspace{14mu}{Resolution}\mspace{14mu}{Height}} = \frac{2{nd}\mspace{14mu}{PPI} \times {Diagonal}\mspace{14mu}{Screen}\mspace{14mu}{Size}\mspace{14mu}{of}\mspace{14mu}{Small}\text{-}{Screen}\mspace{14mu}{Device}}{\sqrt{1 + \left( \frac{{Small}\text{-}{Screen}\mspace{14mu}{Device}\mspace{14mu}{Screen}\mspace{14mu}{Width}}{{Small}\text{-}{Screen}\mspace{14mu}{Device}\mspace{14mu}{Screen}\mspace{14mu}{Height}} \right)^{2}}}$${2{nd}\mspace{14mu}{Resolution}\mspace{14mu}{Width}} = {2{nd}\mspace{14mu}{Resolution}\mspace{14mu}{Height} \times \frac{{Small}\text{-}{Screen}\mspace{14mu}{Device}\mspace{14mu}{Screen}\mspace{14mu}{Width}}{{Small}\text{-}{Screen}\mspace{14mu}{Device}\mspace{14mu}{Screen}\mspace{14mu}{Height}}}$

A second PPI may be first calculated based on the calculatedmagnification ratio, the preferred view screen resolution width andheight, and the diagonal screen size of the passive magnifying devicescreen 712. The second resolution height may then be calculated based onthe second PPI, the diagonal screen size of the small-screen devicescreen 704, and the aspect ratio (the ratio of the small-screen devicescreen 704 width to the small-screen device screen 704 height) of thesmall-screen device screen 704. The second resolution width may then becalculated based on the second resolution height and the aspect ratio ofthe small-screen device screen 704.

FIG. 13 is a flow chart showing a method 1208 of determining distancebetween the small-screen device screen 704 and the passive magnifyingdevice screen 712 with a captured image (e.g., captured image 914).Details may be referred in FIG. 9.

At 1302, a front-facing camera 706 of the small-screen device 702 may beturned on. For the projector system 1100, a rear-facing camera may alsobe used.

At 1304, the front-facing camera 706 of the small-screen device 702 maycapture an image of the passive magnifying device screen 712. For theprojector system 1100, the front-facing or rear-facing camera of thesmall-screen device 1102 may capture an image of a projector screen. Ifthe screen 1110 is a wall or an object that may not have a size that maybe captured in an image, the projector 1106 may project a virtual ruleron the screen 1110. The front-facing or the rear-facing camera maycapture an image of the virtual ruler.

At 1306, the small-screen device 702 may detect a passive magnifyingdevice screen 712 size in the captured image (e.g., captured image 914).For the projector system 1100, the small-screen device 1102 may detect aprojector screen size in the captured image. Or the small-screen device1102 may detect a virtual ruler size in the captured image.

At 1308, the small-screen device 702 may calculate the distance based onthe detected passive magnifying device screen 712 size in the capturedimage (e.g., captured image 914), a reference distance, and a referencepassive magnifying device screen 712 size in a reference image (e.g.,reference image 910). The reference image is captured with thesmall-screen device 702 placed at the reference distance from thepassive magnifying device screen 712. A mathematical formula tocalculate the distance may be:

${806\mspace{14mu}{Distance}} = {{Reference}\mspace{14mu}{Distance} \times \frac{912\mspace{14mu}{Reference}\mspace{14mu}{Width}}{914\mspace{14mu}{Captured}\mspace{14mu}{Width}} \times {Scaling}\mspace{14mu}{Factor}}$

For the projector system 1100, the small-screen device 1102 maycalculate the distance based on the detected projector screen size orthe virtual ruler size in the captured image, a reference distance, anda reference projector screen size or a reference virtual ruler size in areference image. The reference image is captured with the projector 1106placed at the reference distance from the screen 1110. A mathematicalformula to calculate the distance may be:

${1114\mspace{14mu}{Distance}} = {{Reference}\mspace{14mu}{Distance} \times \frac{{Reference}\mspace{14mu}{Ruler}\mspace{14mu}{Size}}{{Captured}\mspace{14mu}{Ruler}\mspace{14mu}{Size}} \times {Scaling}\mspace{14mu}{Factor}}$

FIG. 14 is a flow chart showing a method 1400 of triggering contentresolution adjustment. Content resolution adjustment may be triggeredwhen the small-screen device 702 determines that a portion of thecontent is out of a boundary of the passive magnifying device screen712. If a portion of the content is out of a boundary of the passivemagnifying device screen 712, the resolution of the content may not beoptimal because the portion of the content may not be easily viewable.The resolution of the content on the small-screen device 702 may need tobe adjusted. For the projector system 1100, if a portion of the contentis out of a boundary of a screen 1110 (especially a projector screen),the resolution of the content on the small-screen device 1102 may needto be adjusted. Determining that a portion of the content is out of aboundary of a passive display device screen (e.g., a screen magnifier ora projector screen) may be made by a camera of the small-screen device702 or 1102 taking a photo of the passive display device screen 712 or1110 and detecting out-of-boundary content in the photo.

Content resolution adjustment may be triggered when the small-screendevice 702 or 1102 determines that the first resolution is below aresolution threshold. If the first resolution is below the resolutionthreshold, the viewing experience on the passive display device screen712 or 1110 may not be optimal. The resolution of the content on thesmall-screen device 702 or 1102 may need to be adjusted. The resolutionthreshold may be set on the small-screen device 702 or 1102. Thesmall-screen device 702 or 1102 may compare the first resolution withthe resolution threshold to determine if the first resolution is belowthe resolution threshold.

Content resolution adjustment may be triggered when the small-screendevice 702 or 1102 determines that a first PPI associated with the firstresolution is below a PPI threshold. If the first PPI is below the PPIthreshold, the viewing experience on the passive display device screen712 or 1110 may not be optimal. The resolution of the content on thesmall-screen device 702 or 1102 may need to be adjusted to accommodate ahigher PPI. The PPI threshold may be set on the small-screen device 702or 1102. The small-screen device 702 or 1102 may compare the first PPIwith the PPI threshold to determine if the first PPI is below the PPIthreshold.

Content resolution adjustment may be triggered based on a user request.If the user determines that the viewing experience on the passivedisplay device screen 712 or 1110 is not optimal, the resolution of thecontent on the small-screen device 702 or 1102 may need to be adjusted.The user request (e.g., an indication to adjust) may be received by thesmall-screen device 702 or 1102 in a content resolution adjustmentapplication.

FIG. 15 is a flow chart showing a method 1500 of adjusting contentresolution to maximum screen resolution. At 1502, 1504, 1506, 1508,1510, and 1512, the method 1500 may be referred in the method 1200 atcorresponding 1202, 1204, 1206, 1208, 1210, and 1212, respectively.

At 1514, the small-screen device 702 or 1102 may determine that thesecond resolution is above the maximum screen resolution of thesmall-screen device screen 704 or 1104. The maximum screen resolutionmay be retrieved in a small-screen device 702 or 1102 system informationfile at 1504.

At 1516, the small-screen device 702 or 1102 may output the content inthe maximum screen resolution on the small-screen device screen 704 or1104, instead of in the determined second resolution. The small-screendevice 702 or 1102 may adjust the content resolution on the small-screendevice 702 or 1102. The small-screen device may additionally, oralternatively request the content in the maximum resolution from aremote computing device.

FIG. 16 is a flow chart showing a method 1600 of adjusting contentresolution based on maximum PPI. At 1602, 1604, 1606, 1608, 1610, and1612, the method 1600 may be referred in the method 1200 atcorresponding 1202, 1204, 1206, 1208, 1210, and 1212, respectively.

At 1614, the small-screen device 702 or 1102 may determine that a secondPPI associated with the second resolution is above the maximum PPI ofthe small-screen device screen 704 or 1104. The maximum PPI may beretrieved in a small-screen device 702 or 1102 system information fileat 1604.

At 1616, the small-screen device 702 or 1102 may determine a thirdresolution based on the maximum PPI of the small-screen device screen704 or 1104. The third resolution may be determined in a similar waywith determining the second resolution. However, instead of using themagnification ratio to calculate a second PPI, the maximum PPI may beused.

${3{rd}\mspace{14mu}{Resolution}\mspace{14mu}{Height}} = \frac{{Max}{\mspace{11mu}\;}{PPI} \times {Diagonal}\mspace{14mu}{Screen}\mspace{14mu}{Size}\mspace{14mu}{of}\mspace{14mu}{Small}\text{-}{Screen}\mspace{14mu}{Device}}{\sqrt{1 + \left( \frac{{Small}\text{-}{Screen}\mspace{14mu}{Device}\mspace{14mu}{Screen}\mspace{14mu}{Width}}{{Small}\text{-}{Screen}\mspace{14mu}{Device}\mspace{14mu}{Screen}\mspace{14mu}{Height}} \right)^{2}}}$${3{rd}\mspace{14mu}{Resolution}\mspace{14mu}{Width}} = {3{rd}\mspace{14mu}{Resolution}\mspace{14mu}{Height} \times \frac{{Small}\text{-}{Screen}\mspace{14mu}{Device}\mspace{14mu}{Screen}\mspace{14mu}{Width}}{{Small}\text{-}{Screen}\mspace{14mu}{Device}\mspace{14mu}{Screen}\mspace{14mu}{Height}}}$

At 1618, the small-screen device 702 or 1102 may output the content inthe third screen resolution on the small-screen device screen 704 or1104, instead of in the determined second resolution. The small-screendevice 702 or 1102 may adjust the content resolution on the small-screendevice 702 or 1102. The small-screen device may additionally, oralternatively request the content in the third resolution from a remotecomputing device.

FIG. 17 is a flow chart showing a method 1700 of content resolutionadjustment comprising a small-screen device 1102, a projector 1106, anda screen 1110.

At 1702, the method 1700 may be referred in the method 1200 at 1202.

At 1704, the projector 1106 may project the content from thesmall-screen device screen 1104 onto the screen 1110. The screen 1110may be a projector screen, a wall, or an object that a user may preferto view the content on. The projector 1106 may enlarge the content foran easier view on the screen 1110 compared to the small-screen devicescreen 1104. The projector 1106 may be a component of the small-screendevice 1102 (i.e., a built-in projector). The projector 1106 may also bea separate and independent entity from the small-screen device 1102(e.g., a wireless projector).

At 1706, the method 1700 may be referred in the method 1200 at 1208. Thesmall-screen device 1102 may determine a distance between the projector1106 and the screen 1110. The distance between the projector 1106 andthe screen 1110 may be additionally, or alternatively, input by a useron the small-screen device 1102. The measurement of the distance may bemade by a proximity, ultrasonic, and/or laser sensor on the small-screendevice 1102. The measurement of the distance may be made by afront-facing or rear-facing camera of the small-screen device 1102. Thecamera of the small-screen device 1102 may capture an image of thescreen 1110 (e.g., a projector screen). Based on the size of theprojector screen in the captured image and a reference size of theprojector screen in a reference image, the distance between theprojector 1106 and the projector screen may be calculated. A detailedmethod is shown in FIG. 9. If the screen 1110 is a wall or an objectthat may not have a size that may be captured in an image, the projector1106 may project a virtual ruler onto the screen 1110. The camera of thesmall-screen device 1102 may capture an image of the virtual ruler.Based on the size of the virtual ruler in the captured image and areference size of the virtual ruler in a reference image, the distancebetween the projector 1106 and the screen 1110 may be calculated,similarly as shown in FIG. 9. A mathematical formula for calculating themeasured distance between the projector 1106 and the screen 1110 may be:

${1114\mspace{14mu}{Distance}} = {{Reference}\mspace{14mu}{Distance} \times \frac{{Reference}\mspace{14mu}{Ruler}\mspace{14mu}{Size}}{{Captured}\mspace{14mu}{Ruler}\mspace{14mu}{Size}} \times {Scaling}\mspace{14mu}{Factor}}$

At 1708, the small-screen device 1102 may calculate a size of theprojected content based on the projection distance 1114 andspecifications (e.g., the aperture width, the focal length, etc.) of theprojector 1106. The projection distance 1114 may be limited by a maximumprojection length of the projector 1106. The maximum projection lengthmay be affected by the brightness (such as in lumens) of the projector1106 and the darkness of the environment. The maximum projection lengthand the specifications of the projector 1106 may be input by a user onthe small-screen device 1102, similarly like in FIG. 10 passivemagnifying device system information. A mathematical formula forcalculating the size of the projected content for the projector 1106 maybe:

${822\mspace{14mu}{Projected}\mspace{14mu}{Size}} = {\frac{{816\mspace{14mu}{Projection}\mspace{14mu}{Length}} - {818\mspace{14mu}{Focal}\mspace{14mu}{Length}}}{818\mspace{14mu}{Focal}\mspace{14mu}{Length}} \times 820\mspace{14mu}{Aperture}}$

At 1710, a preferred view screen resolution may be determined. Thescreen 1110 is a passive receiving medium such as a projector screen, awall, an object, etc. There may be no manufactured screen resolution.There may be a preferred view screen resolution that may bring theoptimal viewing experience on the screen 1110. The preferred view screenresolution may depend on the size of the projected content. If the sizeof the projected content is smaller, the preferred view screenresolution may be lower, especially when a bandwidth or a transmissionspeed of a connection with an original data source is low. If the sizeof the projected content is greater, the preferred view screenresolution may be higher. The screen size (if the screen 1110 is aprojector screen), the preferred view screen size (if the screen 1110 isa wall, an object, etc.), and the preferred view screen resolution maybe input by a user on the small-screen device 1102, similarly like inFIG. 10 passive magnifying device system information. The preferred viewscreen resolution may be used to adjust the content resolution.

At 1712, the small-screen device 1102 may adjust the content on thesmall-screen device screen 1104 to a second resolution. The content maybe adjusted to be output in the second resolution by the small-screendevice 1102. The content in the second resolution may additionally, oralternatively, be requested from a remote computing device. The secondresolution may provide the preferred view screen resolution of thecontent on the screen 1110. The second resolution may be determined bymatching the preferred view screen resolution on the screen 1110.

In some aspects, the second resolution may exceed the maximum resolutionof the small-screen device screen 1104. The small-screen device 1102 mayoutput the content in the maximum resolution instead of the secondresolution. In some aspects, a second PPI associated with the secondresolution may exceed the maximum PPI of the small-screen device screen1104. A third resolution may be calculated based on the maximum PPI. Thesmall-screen device 1102 may output the content in the third resolutioninstead of the second resolution.

In the above description of the various embodiments, reference is madeto the accompanying drawings identified above and which form a parthereof, and in which is shown by way of illustration various embodimentsin which aspects described herein may be practiced. It is to beunderstood that other embodiments may be utilized and structural andfunctional modifications may be made without departing from the scopedescribed herein. Various aspects are capable of other embodiments andof being practiced or being carried out in various different ways.

It is to be understood that the phraseology and terminology used hereinare for the purpose of description and should not be regarded aslimiting. Rather, the phrases and terms used herein are to be giventheir broadest interpretation and meaning. The use of “including” and“comprising” and variations thereof is meant to encompass the itemslisted thereafter and equivalents thereof as well as additional itemsand equivalents thereof. The use of the terms “mounted,” “connected,”“coupled,” “positioned,” “engaged” and similar terms, is meant toinclude both direct and indirect mounting, connecting, coupling,positioning and engaging.

Although the subject matter has been described in language specific tostructural features and/or methodological acts, it is to be understoodthat the subject matter defined in the appended claims is notnecessarily limited to the specific features or acts described above.Rather, the specific features and acts described above are described asexample implementations of the following claims.

What is claimed is:
 1. A method comprising: outputting content on ascreen of a first device, said content output in a first resolution;determining one or more capabilities of the screen of the first device;determining one or more capabilities of a screen of a passive magnifyingdevice; determining a distance between the first device screen and thescreen of the passive magnifying device; calculating a magnificationratio based on the passive magnifying device focal length and thedetermined distance; and adjusting the content on the screen of thefirst device to a second resolution based on the calculatedmagnification ratio to provide a preferred view screen resolution of thecontent on the screen of the passive magnifying device.
 2. The method ofclaim 1, further comprising: receiving, by the first device and from aremote computing device, the content in the first resolution and in thesecond resolution.
 3. The method of claim 1, wherein determining one ormore capabilities of the screen of the first device comprisesdetermining a maximum screen resolution, a maximum Pixels Per Inch(PPI), and a screen size of the screen of the first device.
 4. Themethod of claim 3, further comprising triggering the adjusting from thefirst resolution to the second resolution by determining that a firstPPI associated with the first resolution is below a PPI threshold. 5.The method of claim 4, further comprising: determining that a second PPIassociated with the second resolution is above a maximum PPI; adjustingthe content on the screen of the first device to a third resolutionbased on the maximum PPI; and outputting the content on the screen ofthe first device, said content output in the third resolution.
 6. Themethod of claim 1, wherein determining one or more capabilities of thescreen of the passive magnifying device comprises determining a focallength, a preferred view screen resolution, and a screen size of thescreen of the passive magnifying device.
 7. The method of claim 1,wherein the determining the distance comprises: turning on afront-facing camera of the first device; capturing an image of thepassive magnifying device screen; detecting a passive magnifying devicescreen size in the captured image; and calculating the distance based onthe detected screen size in the captured image, a reference distance,and a reference screen size in a reference image, wherein the referenceimage is captured with the first device placed at the reference distancefrom the passive magnifying device.
 8. The method of claim 1, whereinthe determining the distance comprises using one of a proximity,ultrasonic, or laser sensor on the first device to measure the distance.9. The method of claim 1, further comprising triggering the adjustingfrom the first resolution to the second resolution by determining that aportion of the content is out of a boundary of the screen of the passivemagnifying device.
 10. The method of claim 1, further comprisingtriggering the adjusting from the first resolution to the secondresolution by determining that the first resolution is below aresolution threshold.
 11. The method of claim 1, further comprisingtriggering the adjusting from the first resolution to the secondresolution by receiving a user indication to initiate the adjusting. 12.The method of claim 1, further comprising: determining that the secondresolution is above a maximum screen resolution; and outputting thecontent on the screen of the first device, said content output in themaximum screen resolution.
 13. A system comprising: a camera; aprocessor, and memory storing computer readable instructions that, whenexecuted by the processor, configure the system to perform: outputting,at a first resolution, content for projection by a projector onto ascreen; determining a distance between the projector and the screen;calculating a size of the projected content based on the determineddistance; determining a preferred viewing resolution based on thecalculated size of the projected content; and adjusting the outputtedcontent to a second resolution based on the preferred viewingresolution, wherein the determining a distance between the projector andthe screen comprises: projecting a virtual object onto the screen;capturing an image of the virtual object using the camera; detecting avirtual object length in the captured image; and calculating thedistance based on the detected virtual object length in the capturedimage, a reference distance, and a reference virtual object length in areference image, wherein the reference image is captured while theprojector is placed at the reference distance from the screen.
 14. Thesystem of claim 13, further comprising: receiving, from a remotecomputing device, the content in the first resolution and in the secondresolution.
 15. The system of claim 13, wherein the determining thedistance comprises receiving a user input of the distance between theprojector and the screen.
 16. The system of claim 13, whereincalculating the size of the projected content is further based on one ormore specifications of the projector.
 17. A method comprising:outputting content on a screen of a first device, said content output ina first resolution; determining one or more capabilities of the screenof the first device; determining one or more capabilities of a screen ofa passive magnifying device; determining a distance between the firstdevice screen and the screen of the passive magnifying device;calculating a preferred viewing resolution based on the passivemagnifying device focal length and the determined distance; andadjusting the content to a second resolution based on the preferredviewing resolution of the content on the screen of the passivemagnifying device.
 18. The method of claim 17, wherein calculating thepreferred viewing resolution comprises calculating a magnification ratiobased on the passive magnifying device focal length and the determineddistance.
 19. The method of claim 17, wherein the determining thedistance comprises: turning on a front-facing camera of the firstdevice; capturing an image of the passive magnifying device screen;detecting a passive magnifying device screen size in the captured image;and calculating the distance based on the detected screen size in thecaptured image.
 20. The method of claim 17, further comprisingtriggering the adjusting from the first resolution to the secondresolution by determining that the first resolution is below aresolution threshold.